Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study shows that cultured human articular chondrocytes express high levels of 1.4 kb prepro-enkephalin mRNA. Chondrocytes store met-enkephalin intracellularly and secrete this neuropeptide in mature as well as in precursor form. Gene expression is inducible by serum factors. High levels of prepro-enkephalin mRNA are detected in proliferating chondrocytes but not in confluent, contact-inhibited cells. Phorbol myristate acetate and dibutyryl cyclic AMP, but not dexamethasone, increase levels of prepro-enkephalin mRNA. Furthermore, transforming growth factor beta (TGF beta) and platelet derived growth factor (PDGF) upregulate gene expression, whereas retinoic acid, which inhibits chondrocyte proliferation, suppresses both basal and induced gene expression. Using in situ hybridization it is shown that only 1-3% of primary chondrocytes express prepro-enkephalin mRNA, whereas 52 +/- 12% of subcultured cells are strongly positive. Analysis of DNA synthesis, by autoradiography of incorporated [3H]thymidine, shows that these numbers correspond to the percentage of cells in S-phase of the cell cycle. In cultures of primary chondrocytes TGF beta promotes the formation of cartilage nodules and stimulates proliferation of adherent cells. This is associated with high levels of prepro-enkephalin mRNA in proliferating cells but not in contact-inhibited cells in cartilage nodules. In contrast, formation of cartilage nodules, proliferation and the expression of enkephalin are suppressed by interleukin-1 beta. In summary, expression of prepro-enkephalin in human articular chondrocytes is differentially controlled by cartilage regulatory factors and closely associated with cell proliferation.
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PMID:Expression of prepro-enkephalin in human articular chondrocytes is linked to cell proliferation. 131 Sep 29

The Ca2(+)-mobilizing hormone angiotensin II (AII) dose-dependently inhibited the K(+)-induced sustained increase of cytoplasmic Ca2+ concentration in adrenal glomerulosa cells and caused a rapid decrease of cytoplasmic Ca2+ when added to cells already stimulated with K+. These effects of AII on the K(+)-induced Ca2+ signal were mimicked, although less effectively, by other Ca2(+)-mobilizing agonists such as [Arg8]vasopressin (AVP) and thapsigargin. Phorbol esters did not show such effects, nor did corticotropin (ACTH), a secretagogue acting via cyclic AMP. The K(+)-stimulated initial 45Ca2+ uptake, a measure of Ca2+ entry into glomerulosa cells, was also prevented by AII pretreatment, and was inhibited by AVP, but not by ACTH. The stimulatory effect of K+ on aldosterone production, however, was not inhibited by AII, and the AII-induced aldosterone production was further increased by increasing K+. These data indicate that AII is able to inhibit static increases in cytoplasmic Ca2+ by inhibiting Ca2+ entry through voltage-sensitive Ca2+ channels and, possibly, by activating Ca2+ extrusion from the cells. It is also concluded that the Ca2+ signal evoked by AII is very efficient in stimulating hormone secretion, and the secretory response of the cells becomes more sensitive to any further increase of Ca2+ entry through voltage-sensitive Ca2+ channels.
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PMID:Angiotensin II inhibits K(+)-induced Ca2+ signal generation in rat adrenal glomerulosa cells. 184 39

Corticotropin (ACTH)-releasing factor, vasoactive intestinal peptide, and catecholamines--hormones that stimulate ACTH secretion and cAMP generation--increased cytosolic calcium in AtT-20 cells. The increase in intracellular calcium is presumably a consequence of the stimulated cAMP synthesis, since forskolin, an activator of the catalytic unit of adenylate cyclase, and the cAMP analog 8-bromoadenosine 3',5'-cyclic monophosphate (8Br-cAMP) also increased the cytosolic levels of this ion. Pretreatment with somatostatin, a neuropeptide that inhibits stimulation of the adenylate cyclase system and the secretion of ACTH blocked the increase of cytosolic calcium. The effect of 8Br-cAMP, which bypasses the cyclase, was not inhibited by somatostatin pretreatment. The source of the increased calcium appears to be mainly extracellular. This is indicated by the inability of the secretagogues to increase cytosolic calcium in a medium deprived of this ion or in the presence of blockers of voltage-gated calcium channels. The involvement of calcium channels in the calcium rise evoked by the secretagogues was supported by experiments using the whole-cell patch-clamp technique. In these experiments 8Br-cAMP increased voltage-dependent calcium currents. These results suggest the following chain of events in the receptor-mediated elevation of cytosolic calcium and the concomitant release of ACTH from AtT-20 cells: hormone-receptor binding----cAMP synthesis----protein kinase activation----calcium channel activation----increase in cytosolic calcium----many steps----ACTH release. Phorbol myristate acetate, a compound which does not stimulate cAMP generation but enhances the release of ACTH in AtT-20 cells, decreased the cytosolic calcium level.
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PMID:Hormone secretagogues increase cytosolic calcium by increasing cAMP in corticotropin-secreting cells. 241 78

The purpose of the present study was to further characterize the inhibition by prostaglandin E2 (PGE2) of adrenocorticotropin (ACTH) and beta-endorphin release from rat anterior pituitary fragments in vitro. Peptide hormone release was induced by vasopressin, which initiates secretion via cell surface receptors, or by secretagogues which can mimic various post-receptor mechanisms and the effect of PGE2 was examined. Concentration-response curves of the effect of vasopressin on the release of beta-endorphin-like (beta-End-IR) and ACTH-like immunoreactivity (ACTH-IR) were constructed in the absence or presence of a fixed concentration of PGE2. The concentration-response curve of vasopressin was shifted to the right about 8-fold by PGE2 (1 mumol/l) without altering the maximum effect. PGE2 (60 nmol/l-1 mumol/l) markedly reduced beta-End-IR release induced by 8-bromoadenosine-3',5'-cyclic-monophosphate (8Br-cAMP) (1 mmol/l). Omission of Ca2+ from the incubation medium did not prevent PGE2-induced inhibition of 8Br-cAMP-evoked secretion. 4 beta-Phorbol, 12 beta-myristate, 13 alpha-acetate (PMA) stimulated beta-End-IR and ACTH-IR release in a concentration-dependent manner. This effect was not blocked by indometacin or eicosatetraynoic acid. PG E2 (greater than 100 nmol/l) reduced PMA (100 nmol/l)-elicited secretion by about 50%. PG E2 (1 mumol/l) almost halved beta-End-IR release caused by K+ (30 mmol/l). After pre-incubation in Ca2+-free medium, re-introduction of Ca2+ (1.3 mmol/l) elicited beta-End-IR release. This response was abolished by PG E2 (1 mumol/l). The addition of Ba2+ (10 mmol/l) to a Ca2+-free medium markedly enhanced beta-End-IR release.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of prostaglandin E2 on ACTH and beta-endorphin release from rat adenohypophysis in vitro after secretagogues which can mimic various first or second messengers. 301 94

Previous studies have shown that phorbol esters and lithium each stimulate the secretion of adrenocorticotropic hormone (ACTH) by the anterior pituitary tumor cell line AtT20/D16-16. Pretreatment with either lithium or phorbol ester desensitizes the cells to subsequent stimulation by phorbol ester. An early consequence of phorbol ester action in other systems is the translocation of protein kinase C from cytosol to membranes. We have assayed protein kinase C activity in cytosol and membranes of AtT20 cells after treatment with phorbol dibutyrate, lithium, or other agents that stimulate secretion of ACTH in these cells. Phorbol dibutyrate clearly induced translocation of protein kinase C, but lithium treatment did not cause translocation itself, nor did pretreatment with lithium affect the translocation induced by phorbol dibutyrate. These results are consistent with a role for translocation of protein kinase C in the stimulatory and desensitizing effects of phorbol esters but fail to implicate translocation in the actions of lithium on AtT20 cells.
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PMID:Translocation of protein kinase C in anterior pituitary tumor cells. 302 60

We show that Cloudman melanoma cells undergo rapid arborization in response to [Nle4,D-Phe7]alpha-melanocyte-stimulating hormone, a potent analogue of alpha-melanocyte stimulating hormone (alpha-MSH). The arbors were established by extension of processes and resembled dendrites. We used this system to study the regulation of cell shape. alpha-MSH is known to induce increases in cAMP levels, and agents such as forskolin and isobutylmethylxanthine that led to increased cAMP also caused arborization. However, equally dramatic arbors were formed after incubation with the protein kinase C inhibitor H-7 [1-(5-isoquinolinesulfonyl)-alpha-methyl-piperazine]. Phorbol diesters that activate protein kinase C led to cell rounding and antagonized alpha-MSH. The actions of protein kinase C cannot be rationalized in terms of indirect effects on cAMP: neither H-7 nor phorbol diesters alone altered cAMP levels, nor did they affect the increase in cAMP induced by MSH. We show also that MSH produced longer-term effects that cannot be mimicked by cAMP. Specifically, even in the continued presence of alpha-MSH, arborization was followed by morphological reversal to the unstimulated flattened configuration within 2 hr. (This did not occur with other agents that increase cAMP or with H-7.) Most importantly, whereas MSH-induced arborization occurred in the presence of cycloheximide, actinomycin D, or in enucleated cells, the reversal of arborization did not. Thus, MSH induced a program of rapid shape change that was dependent on new protein synthesis and gene transcription.
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PMID:Regulation of cell shape in the Cloudman melanoma cell line. 303 40

Retinoic acid was found to be a potent stimulant of pigmentation in human Hs939 melanoma cells. Exposure to 1 microM retinoic acid for longer than four days caused both a decrease in the rate of cell proliferation and a concomitant increase in melanogenesis. These effects of retinoic acid progressed lin-early in a time-dependent and a dose-dependent fashion such that at the end of a seven-day treatment cell growth was inhibited by approximately 65%, and both melanin content and tyrosinase activity increased more than three-fold over the control. Interpolation of the dose-response curves indicated that 3 nM retinoic acid would cause half-maximal melanogenesis stimulation. No elevation in the level of cyclic adenosine 3':5'-monophosphate could be detected in the melanoma cells following various periods of exposure to retinoic acid, and the cells were unresponsive to alpha-melanocyte-stimulating hormone. In the presence of the tyrosinase inhibitor phenylthiocarbamate, retinoic acid was capable of inhibiting cell proliferation without enhancing melanin synthesis. The tumor promoter phorbol myristate acetate did not affect either the proliferation or the differentiation of the Hs939 melanoma cells. However, the enhancement of melanogenesis by 1 microM retinoic acid was inhibited by 66% in the presence of 0.1 microM phorbol myristate acetate. The tumor promoter did not reverse the growth-inhibitory effect of retinoic acid. Phorbol, a non-tumor promoter, was effective. Other retinoids, such as 13-cis-retinoic acid, retinyl acetate, nd the trimethylmethoxyphenyl analog of retinoic acid, also inhibited the proliferation and enhanced melanin production in the Hs939 cells. In contrast, retinyl palmitate, the phenyl analog of retinoic acid, and the pyridyl analog of retinoic acid were ineffective.
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PMID:Stimulation of melanogenesis in a human melanoma cell line by retinoids. 625 61

The effects of various neuropeptides on human plasma cells were studied. Of the various neuropeptides tested, vasoactive intestinal peptide (VIP) enhanced Ig production and growth in human plasma cell lines, IM-9 and AF-10, and in plasma cells generated in vivo (four out of four patients with plasma cell leukemia) and in vitro. In contrast, other neuropeptides (neuropeptide Y, somatostatin, substance P, peptide YY, neurokinin A, calcitonin gene-related peptide, chole-cystokinin octapeptide, and beta-endorphin) were ineffective. Moreover, VIP-induced enhancement was specifically blocked by VIP receptor antagonist. Among the various cytokines, IL-6, GH, and insulin-like growth factor I (IGF-I) also enhanced Ig production and thymidine uptake in plasma cells. However, VIP-induced enhancement was not mediated by IL-6, GH, or IGF-I because antibodies to these cytokines failed to block VIP-induced enhancement. Phorbol 12,13 dibutyrate enhanced Ig production and thymidine uptake in plasma cells, and the Phorbol 12,13 dibutyrate-induced enhancement was blocked by H7 (a protein kinase C inhibitor) but not by H8 (a protein kinase A inhibitor). Similarly, VIP-induced enhancement was blocked by H7 but not by H8. Collectively, VIP enhances plasma cell responses via mechanisms that may involve protein kinase C.
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PMID:Vasoactive intestinal peptide enhances immunoglobulin production and growth in human plasma cells via mechanisms that may involve protein kinase C. 876 69

Activation of protein kinase C (PKC) stimulates adrenocorticotropin (ACTH) release synergistically in the presence of corticotropin releasing factor (CRF). We examined the effect of a cyclic nucleotide-specific phosphodiesterase inhibitor, 1-isoamyl-3-isobutylxanthine (IIX), on arginine vasopressin (AVP)-induced ACTH release and intracellular cAMP accumulation in normal rat anterior pituitary cells. IIX alone elevated intracellular cAMP accumulation. IIX potentiated AVP-induced ACTH release synergistically without further increase in cAMP accumulation, suggesting that synergistic ACTH release has an alternative mechanism other than the synergistic elevation of intracellular cAMP accumulation which has been reported. Phorbol 12-myristate-13-acetate (PMA) also induced synergistic ACTH release when incubated with IIX. IIX had no additional effect on ACTH response when incubated with maximal dose of CRF, forskolin or 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP). Moreover, the combination of PMA and 8-Br-cAMP produced synergistic ACTH response. In conclusion, the synergistic ACTH release from rat pituitary corticotrophs occurs at least in the presence of directly activating events of PKC and PKA as well as PKC-induced inhibition of phosphodiesterase activity.
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PMID:Mechanism involved in synergistic adrenocorticotropin response to activating protein kinase-A and -C in rat anterior pituitary cells. 1021 Feb 88

The regulation of cellular levels of adrenocorticotropin hormone (ACTH) in response to stimulated secretion was investigated to define the extent of cellular depletion of ACTH and subsequent increases to replenish ACTH levels in anterior pituitary cells (in primary culture). Treatment of cells with secretagogues for short-term incubation times (hours) resulted in extensive depletion of cellular ACTH. Corticotropin releasing factor (CRF) induced depletion of cellular levels of ACTH by 60-70% of control levels. The CRF-induced reduction of cellular ACTH was inhibited by the glucocorticoid dexamethasone. Phorbol myristate acetate (PMA), which stimulates protein kinase C (PKC), reduced ACTH levels by 50-60%. Forskolin, a stimulator of cAMP production, produced a moderate reduction in cellular ACTH. During prolonged incubation of cells (2 days) with these secretagogues, further reduction of ACTH levels by 70-80% was observed. However, increased cellular levels of ACTH occurred with continued treatment of cells with secretagogues, which provided nearly complete replenishment of cellular ACTH after 5 days treatment with secretagogues. Notably, the rising levels of cellular ACTH were inhibited by the aspartyl protease inhibitor acetyl-pepstatin A, and by the cysteine protease inhibitor E64d. These results demonstrate that depletion and recovery of ACTH levels are coordinately regulated, and that the increases in cellular levels of ACTH during the recovery phase involves participation of aspartyl and cysteine proteases. Thus, aspartyl and cysteine proteases may be involved in the cellular metabolism of ACTH.
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PMID:Regulation of ACTH levels in anterior pituitary cells during stimulated secretion: evidence for aspartyl and cysteine proteases in the cellular metabolism of ACTH. 1289 58


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